<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 100px;
            height: 100px;
            background-color: pink;
        }
    </style>
</head>

<body>
    <div></div>
    <script>
        var div = document.querySelector('div');
        var flag = 0;
        div.onclick = function() {
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                this.style.width = "200px";
                this.style.height = "200px";
                this.style.backgroundColor = "red";
                flag = 1;
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                this.style.height = "100px";
                this.style.backgroundColor = "pink";
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</body>

</html>